Shuttle valves are known from the prior art wherein the flow of a fluid or a gas may be selectively controlled so as to direct the flow of same in various directions through a valve or a valve housing. FIGS. 1, 2 and 3 are exemplary of shuttle valves which are known from the prior art. Such shuttle valves make possible the change of the direction of the flow of a fluid or a gas from one flow passage or channel to another so as to selectively direct the flow of the fluid or gas through the shuttle valve.
In FIG. 1, a prior art shuttle valve 10 is illustrated which comprises a valve housing 16, having an inlet 14 and outlets 16 and 18. The inlets and outlets are connected in a flow-through arrangement so as to facilitate the flow of a fluid or gas through the shuttle valve. The direction of flow of the fluid or gas depends on the position of a valve slide 20 which is located within the valve housing. The valve slide 20 is actuated by an external means such as by a hand wheel 22. The valve slide 20, under the control of the hand wheel 22, can be shuttled between the valve seating 24 which is associated with flow passage 50 and the valve seating 26 which is associated with flow passage 60 so as to selectively direct the flow of a medium through the shuttle valve 10.
The prior art shuttle valve of FIG. 1 is undesirable as the sharp turn of the flow of the fluid or gas, which results from the design of said valve, creates a high flow resistance which results in considerable pressure losses in the flow pressure of the fluid or gas. Another disadvantage of the shuttle valve of FIG. 1 lies in the fact that turbulent flows may also result. Further, if the valve is used improperly, the valve slide could assume an intermediate position whereby a fluid or gas flow would exist through both flow passages. The prior art shuttle valve of FIG. 1 may also require numerous and tedious turns of the hand wheel 22 which may further prevent a completely synchronous operation with other shuttle valves.
FIG. 2 illustrates another prior art shuttle valve 10 wherein a rotatable valve arrangement requires the actuation of a locking device 28, which typically needs to be rotated. A shaft 22, which is further connected to an inner housing part 30 and a valve slide 40, can be rotated and the flow of a fluid or gas can be directed from flow passage 60 to flow passage 50 or vice versa. In the prior art shuttle valve of FIG. 2, the equivalent of two 45.degree. elbows are placed back to back in order to complete a flow channel. While this arrangement results in low pressure losses, the actuation of the rotatable valve arrangement is quite complicated. In order to change the direction of the flow of a fluid or gas from flow passage 50 to flow passage 60, or vice versa, the locking device must be actuated in order to move the shaft 22 downwards which, due to the mechanical connection between the shaft and the inner housing part 30 and valve slide 40, must be moved downward in order to move the inner housing part 30 and the valve slide 40 downward and away from the valve seats adjacent the flow passages.
The valve slide 40 is connected to the inner housing part 30 and closes off the opposite flow passage. The inner housing part 30 and valve slide 40 arrangement are rotated by the rotation of shaft 22 so as to align these elements with their respective flow passages upon which time the shaft 22 and the inner housing part 30 and valve slide 40 arrangement are then moved upwardly by the rotation of the locking device 28 so as to cause the inner housing 30 and the valve slide 40 to be seated against the seating surfaces of their respective flow passages. The downward movement of the inner housing 30 and valve disk 40 arrangement is required so that this rotation can be facilitated.
The prior art shuttle valve 10 of FIG. 2 is disadvantageous because an actuation means is required to actuate the locking device 28 in order to move the shaft 22 and the inner housing 30 and valve slide 40 arrangement downwards and away from the valve seats. Further, a second actuation means is necessary to rotate the shaft 22 so as to rotate the inner housing 30 and valve slide 40 each from one flow passage to the opposite flow passage. It is most difficult to automate this above described double actuation operation and for this reason, the shuttle valve of FIG. 2 is undesirable. Further, the inner valve, which comprises inner housing 30 and valve slide 40, is comprised of several components which requires costly assembly and maintenance procedures.
FIG. 3 illustrates yet another prior art shuttle valve 10 which is the subject of U.S. Pat. No. 4,964,435. In the prior art shuttle valve 10 of FIG. 3, a shaft 22, having a square head 240 is utilized to rotate bushings 98 and 100. The portion of shaft 22 carrying bushings 98 and 100 is eccentric to the upper centerline of shaft 22 so that the rotation of the bushing 98 will also be eccentric. A lever 82 is connected to the bushing 98 and has connected thereto a valve disk 20. The lever 82 can rotate on the bushing 98. In order to keep the lever 82 from rotating too easily, belleville washers 136 are utilized which act as a spring and which are tightened by nut 142 on shaft 22.
As the nut is tightened, the belleville washers are compressed and squeeze bushings 98 and 100 on lever 81. This action causes the shaft 22 to turn lever 82 and therefore causes the valve disk 20 connected thereto to rotate. Once the valve disk 20 is rotated so as to align with the valve seat corresponding to the flow passage to be shut off, the eccentric portion of the shaft 22 serves to push the valve disk 20 up against the valve seat corresponding to the flow passage. The shuttle valve of FIG. 3 requires rotation of the shaft 22 by approximately 270.degree., which includes an approximately 180.degree. rotation from alignment with one flow passage to the opposite flow passage and the further rotation of the shaft so as to facilitate valve disk seating and unseating.
The shuttle valve 10 of FIG. 3 is disadvantageous as actuators for the 270.degree. rotation are not commonly available and further because the presence of the moving parts of the inner assembly in the flow path results in undesirable flow resistance and increased flow losses. The shuttle valve of FIG. 3 is also undesirable as it requires travel stops to aid in the alignment of the valve disk 20 with the flow passage and further because no positive linkage exists between the shaft 22 and the valve disk 20 linkage.
The shuttle valve of the present invention addresses the shortcomings of the prior art shuttle valves described herein and provides a shuttle valve which can operate with more commonly available actuators such as 180.degree. actuators or actuators that require less rotation while at the same time providing a means by which to provide a positive linkage between the actuator shaft and the inner valve assembly part while at the same time providing a shuttle valve having reduced pressure losses and reduced manufacturing and maintenance costs.